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A voyage to India, Africa & China

The use of natural products for medical reasons has a long tradition in the West. But Asia and Africa also boast a rich and diverse medical culture that is based on drugs derived from plants, minerals and metals. To reflect this global phenomenon, whose roots go back thousands of years, we have asked experts from India, Africa and China to shed light on the respective practices in their home countries. We want to thank Ashwini Mathur and Vinay Mahajan from Novartis in India who wrote an illuminating essay on the scope of Ayurveda. Likewise, we express our gratitude to Fidelis Cho-Ngwa, Manfo T. Pascal, Jonathan A. Metuge and Moses Samje from the University of Buea in Cameroon who provided us with an excellent overview of the state of natural products research in Cameroon. Last but not least, we are grateful to Yang Ye from the Shanghai Institute of Materia Medica for his elegant explanation of traditional Chinese medicine.

Text by Goran Mijuk, photos by Jan Raeber

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This article was originally published in April 2014.

Ayurveda’s exact origin is controversial. But its conceptual framework developed and matured between 2500 BC and 500 BC in India. The word “Ayurveda” is derived from “ayus,” meaning life, and “veda,” meaning knowledge; thus, Ayurveda literally means “knowledge/science of life.” It is the ancient Indian system of healthcare and longevity.

Ayurveda takes a holistic view of an individual. It defines good health as a balanced metabolism resulting in a healthy state of being. It defines an illness or a disease as an imbalance in metabolism, which can arise from the body or the mind because of external factors or intrinsic causes. Ayurvedic treatment is thus aimed at the patient as an organic whole and consists of a combination of diet, drugs and various physical and mental activities, which depends on each individual. Ayurveda has a large documented history, which is mainly written in Sanskrit and covers different aspects of disease, therapy and pharmacy.

Medicinal preparations in Ayurveda are often complex mixtures, including plant and animal-derived products, minerals and metals. Of these, plants form a dominant part of the Ayurvedic Pharmacopoeia.

The Charaka Samhita, which dates from 900 BC, is the first recorded treatise that is fully devoted to the concepts and practice of Ayurveda; its primary focus is therapeutics. The treatise lists 341 plants and plant products for medical use. Another landmark text is the Sushruta Samhita (600 BC) which looks at surgery. It describes 395 medicinal plants, 57 drugs of animal origin, and 64 minerals and metals as therapeutic agents. Another important authority in Ayurveda was Vagbhatta, who practiced in the seventh century AD. His work Ashtanga Hridaya about the principle and practice of medicine is considered a masterpiece.

Given their thematic scope and detailed knowledge, Ayurvedic texts were much respected in neighboring countries, as evidenced by their translation into Greek (300 BC), Tibetan and Chinese (300 AD), Persian and Arabic (700 AD) and several other Asian languages.

There are approximately 1250 Indian medicinal plants that are used in formulating therapeutic preparations. A fairly comprehensive account of early research covering the modern period up to the early 1930s was put together by RN Chopra in his Indigenous Drugs of India.

Among the best-known plants is the Rauwolfia serpentina. Roots of the plant are mentioned in Ayurveda for the treatment of hypertension, insomnia and insanity. Significant pharmacologic, clinical and chemical work on the plant was carried out in India. This attracted the attention of CIBA, which succeeded in isolating the sedative principle, reserpine, a minor alkaloidal constituent, in 1952. Commiphora wightii, a small tree belonging to the family Burseraceae, also made an impact on modern medicine. When injured, the plant exudes a yellowish gum resin that soon solidifies to an agglomerate of tears with a balsamic odor similar to myrrh. This gum resin – renowned in Ayurveda medicine for the treatment of inflammatory disorders, among others – was tested with modern methods in the 1970s, which eventually led to the isolation and characterization of two anti-hyperlipoproteinemic compounds.

Ayurveda, and other similar systems, represent a valuable resource for the development not only of medicinal preparations but also of nutraceuticals and cosmeceuticals. However, these claims must be critically evaluated in terms of modern scientific parameters. Taking this aspect into account, it may not be an overstatement to say that the 21st century could become the era of pluralism in healthcare. The human population, the world over, is grappling with new healthcare problems, which are unlikely to be solved by a single approach. Therefore, the search for complementary healthcare solutions should be promoted. As an evidence-based health science Ayurveda has evolved and matured over the last two millennia and therefore has the potential to be a significant contributor for complementary healthcare solutions.

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Prunus africana.

Africa, by virtue of its abundance of sunshine and, in many situations, plenty of moisture, is well endowed with both variety and abundance of living things. For example, the Cape is a center of plant diversity of global importance. Meanwhile the Democratic Republic of the Congo and Tanzania are centers of bird diversity.

Although the biodiversity of its fauna has yet to be fully explored and is therefore, grossly underestimated, it is known that about a quarter of the world’s 4700 or so species of mammals occur in Africa, with close to 1000 of those in sub-Saharan Africa alone; more than 2000 bird species, constituting more than a fifth of the 10 000 or so bird species in the world, are estimated to originate in Africa.

Some authors have concluded – correctly or incorrectly – that the floral biodiversity of Africa is generally lower than that of other tropical areas. Again, this conclusion could be the result of inadequate surveys. Despite this common view, it is known that 5 of the 20 global centers of plant diversity are located in Africa, including the Cameroon-Guinea center, the Capensis center and the Madagascar center. Microbial diversity has been difficult to quantify, but many such species are found only in Africa. The humid tropical climate is particularly good for microbial life.

The rich biodiversity of Africa provides, among other things, food, building materials and medicines for many ailments, especially for tropical diseases: Trypanosomiasis or sleeping sickness, malaria and onchocerciasis, which is also known as river blindness. Yet ingredients are also used to treat non-communicable diseases, such as diabetes and hypertension, which are currently on the rise in the continent due to changing lifestyles.

The indigenous people of Africa use traditional medicine for their primary healthcare needs, as medicinal plants are the most easily accessible and affordable health resource available to many local communities and at times the only therapy that exists in many parts of rural Africa. The World Health Organization estimates that over 80 percent of the emerging world’s population relies on traditional medicine. The challenges in the use and development of medicines from plants in Africa include the lack of standardization and little to no quality control. Risk of undocumented long-term side effects, microbial contamination due to poor handling, poor diagnosis and indiscriminate dosing compound the existing challenges. Likewise, formulation of medicines from plants in crude drug form – a process that requires training and experience – is not common in Africa. Popular examples of medicinal plants of Africa include the Afromontane tree Prunus africana, Aloe vera, Morinda lucida, Pausinystalia yohimbe (Yohimbe), to name but a few. As such, the medicinal plants of Africa provide a major opportunity to identify new lead molecules for the modern pharmaceutical industry. In our laboratory, when extracts of plants acclaimed to be able to treat onchocerciasis have been tested in vitro, more than 75 percent of them have shown good to excellent activity.

As of now, only a handful of Africa’s medicinal plants have been screened for their acclaimed pharmacological effects, and very few active pure compounds have been isolated from the plants, reflecting the state of low technological and industrial development.

Finally, since some 40 percent of all modern drugs in use are derived from natural products or their derivatives, the development of a pharmaceutical strategy to make use of the medicinal plants, fauna and microorganisms of Africa, especially to cure the endemic neglected tropical diseases, should be an R&D priority area.

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Artemisia annua.

Chinese medicine has played a significant role in the mainstream healthcare system of the country for thousands of years. It has its own theoretical basis and long-term practices. Its comprehensive system features the use of large numbers of herbal material.

In traditional Chinese medical theory, every herb has its basic characteristics in the understanding of the human body’s physiological and pathological behaviors as well as diagnosing and curing diseases. These main characteristics include four natures, five flavors, ascending-descending-floating-sinking, channel tropism, toxicity, compatibility, and drug contraindication.

The four natures, also known as four temperature properties, refer to cold (han), hot (re), warm (wen), and cool (liang). Five flavors refer to taste properties of herb, namely sour (suan), sweet (gan), bitter (ku), spicy (xin), and salty (xian). Ascending-descending-floating-sinking is relevant to the four tendencies of effects when traditional Chinese medicine reacts with the human body. On the basis of these properties, channel tropism further connects the therapeutic effects of traditional Chinese medicine to the specific parts of the body. Moreover, toxicity indicates the bias property of traditional Chinese medicine. Compatibility is about how to apply two or more herbs together based on a patient’s physical condition and the herb’s property. Drug contraindication encompasses the knowledge of herbs that cannot be applied together, for example.

Thousands of years of practical experience has turned traditional herbal medicine into one of the main approaches to healthcare in China.

Herbs were documented in a number of medicinal books and official documents. For example, the compendium Materia Medica (本草纲目), one of the most famous medicinal classics, collected 1892 medicinal materials, of which 1095 were herbs. Based on such cumulated knowledge, Chinese scientists can now turn to records in medicinal classics to identify herbs which may contain molecules with specific therapeutic effects. The selection of plants is more informative and directional in comparison with random collection and screening. Therefore, the probability of identifying biologically active small molecules might be higher.

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Rauwolfia.

The successful discovery of artemisinin (qin-ghaosu) from Artemisia annua as an effective anti-malaria therapy has saved millions of lives around the world. In an article published in Nature Medicine, Professor Youyou Tu, the Lasker Prize winner in 2011, noted after investigating more than 2000 Chinese herbal prescriptions that the medicinal herb Qinghao was one of the most frequently used herbs for the treatment of malaria. The fresh juice of Qinghao for alleviating malaria symptoms was recorded by Ge Hong (281–341 AD). In his Handbook of Prescrip-tions for Emergencies he writes: “A handful of Qinghao immersed with 2 liters of water, wring out the juice and drink it all.”

Another representative example is depside salt from Salvia miltiorrhiza, a traditional medicinal herb known as Danshen. Danshen is widely used in clinics to improve blood circulation, relieve blood stasis, and treat coronary heart disease. Depside salt is a mixture comprising the active ingredients magnesium litho-spermate B and its five analogs. China’s State Food and Drug Administration granted a new drug license for this mixture and its injection in May 2005. According to Lijiang Xuan, the chief scientist of the program at Shanghai Institute of Materia Medica, Chinese Academy of Sciences, depside salt not only has definite chemical components, but also shows a clear curative effect on coronary heart disease and angina, based on trials carried out in 460 patients and a clear mechanism of action as well.

These two cases gave us a glimpse of successful drugs derived from traditional medicines. Compared with those of many other phytochemical discoveries in drug development, the route to the discovery of new drugs from traditional medicines is short and directional. Professor Zhibi Hu, member of the Chinese Academy of Engineering, said in Nature Biotechnology: “This success means China’s biopharmaceutical industry can develop innovative drugs by investigating the chemical ingredients of traditional Chinese medicines whose clinical effects have long been observed. Compared with developing new compounds from scratch, the approach is potentially more rapid and less expensive.”

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